DE102012105855A1 - Apparatus for processing rubber and processing method therefor - Google Patents

Abstract

The present invention provides an apparatus for processing rubber. The device is equipped with a closed kneading chamber (5); a filling opening (3) for filling a material in the kneading chamber (5); a rotor (6) for stirring the material in the kneading chamber (5); a control unit (11) for automatically controlling the rotational speed of the rotor (6); and a temperature sensor (13) for detecting the internal temperature of the kneading chamber (5) and sending the detected information regarding the internal temperature to the control unit (11). The control unit (11) automatically controls the rotation speed with a PID control configured to try to set the actual temperature until the lapse of a set control time set for the state in which the material containing the rubber component in the Kneading chamber (5) is in agreement with the target temperature, on the basis of the actual temperature information and a target temperature information related information.

Description

Background of the Invention Field of the Invention

The present invention relates to an apparatus for processing rubber and a processing method therefor.

Description of the Related Art

Rubber is generally processed in a sequence of mixing, rolling / extruding and molding. Of these, the mixing step includes a masticating step and a kneading step. The kneading step is carried out to mix and distribute additives finely and homogeneously in the raw rubber. On the other hand, the masticating step is performed prior to the kneading step to soften and homogenize the rubber itself, so that the additives in the subsequent kneading step can be easily mixed and dispersed in the raw rubber.

The kneading step is generally divided into two steps, A kneading and B kneading. A-kneading is a step in which an agent is added and the mixture is kneaded, which agent contains a reinforcing agent such as silica and carbon black, but excludes vulcanization components (e.g., vulcanization agents and vulcanization accelerators). The B-kneading is a step in which vulcanization components are added to the material obtained by the A-kneading step, and the mixture is then kneaded.

• (1) Zuerst erfolgt eine Beschreibung des Mastizierschrittes. Das Mastizieren dient der Ausübung eine Scherkraft auf das Gummimaterial, um dessen Molekülketten zu spalten, dessen Viskosität zu vermindern und dem Material Plastizität zum Formen zu verleihen.

At each masticating step, A-kneading and B-kneading, temperature control plays a critical role. (For example, refer to the unexamined published Japanese patent application (Kokai). JP-A-Hei 7-227,845 , Japanese Published Unexamined Patent Application (Kokai) JP-A-2004-352 831 , Japanese Published Unexamined Patent Application (Kokai) JP-A-2007-8 112 and the unexamined published Japanese patent application (Kokai) JP-A-2007-320184 Referred to).

• (1) First, a description will be made of the masticating step. Masticating serves to exert a shearing force on the rubber material to cleave its molecular chains, reduce its viscosity, and impart plasticity to the material.

There are two types of mastication, low temperature masticating and high temperature masticating. As in the unexamined Published Japanese Patent Application (Kokai) JP-A-Hei 7-227,845 For example, when masticating at high temperature during kneading, a peptizer (ie, a masticating promoter) was conventionally added.

Masticating at low temperature is a mechanical masticating that occurs at a temperature of up to about 110 ° C. In this masticating step, the longer sections of molecular chains are selectively cleaved to reduce the molecular weight. On the other hand, high temperature masticating is a chemical masticating which occurs at a higher temperature, e.g. B. 120 ° C to 180 ° C, with the addition of a peptizer to cause a chemical reaction and thus to cleave the molecular chains.

Masticating natural rubber occurs in a closed-type mixer (eg, a Banbury mixer). In the course of kneading the rubber, heat is generated, so that the temperature of the rubber increases. In particular, holding the gum at a high temperature, e.g. B. 150 ° C to 180 ° C, in a closed room for a long period of time, as in the case of mastication at high temperature, for burning (or scorching) of the rubber. Therefore, it is common practice to add a peptizer in an early step to give plasticity to the raw rubber and thus shorten the time for masticating.

In the case of high temperature mastication using a peptizer, the molecular chain is cleaved at the reaction point of the peptizer regardless of its molecular weight. It is believed that thereby, after mastication, various low to high molecular weight compounds remain in the rubber composition. This can lead to segregation of the peptizer and further increase the unevenness of the reaction.

On the other hand, as described above, the mechanical masticating performed at a low temperature selectively cleaves the higher molecular weight portions so that the weight of the molecules in the rubber compound is uniformly reduced. Mechanical masticating is thus of greater advantage in stabilizing the chemical properties of the gum after mastication.

In view of this, the masticating step is preferably carried out solely as mechanical masticating. In the conventional method, the attempt to perform the mechanical masticating alone shows the problem that the heat associated with the kneading of the rubber increases the temperature of the rubber.

• (2) Nunmehr folgt eine Beschreibung des A-Knetens. In den letzten Jahren wurde anstelle von Ruß Siliciumoxid bzw. Silica als Verstärkungsmittel verwendet, das beim Schritt des A-Knetens zugesetzt werden soll. Silica hat jedoch den Nachteil, dass seine Fähigkeit, Gummi zu verstärken, geringer als die von Ruß ist. Wenn Silica in eine Gummikompo-nente eingemischt wird, wird folglich ein Silankopplungsmittel zugesetzt, um das Ver-stärkungsvermögen zu verbessern. Wenn das Silankopplungsmittel als Zusatz zugegeben wird, wird es durch seine Kopplungsreaktion am Silica fixiert und reagiert ferner mit der Gummikomponente, sodass das Dispersionsvermögen des Silica im Gummi und das Verstärkungsvermögen verbessert werden.

In other words, it increases the temperature in the course of masticating and exceeds the temperature range suitable for mechanical masticating, in which the rubber obtains sufficient plasticity, so that vulcanization of the rubber occurs. Against this background, there is a need for a method that allows for mastication while maintaining the most appropriate temperature.

• (2) Next is a description of A-kneading. In recent years, instead of carbon black, silica has been used as the reinforcing agent to be added in the A-kneading step. However, silica has the disadvantage that its ability to reinforce rubber is lower than that of carbon black. Thus, when silica is mixed in a rubber component, a silane coupling agent is added to improve the reinforcing power. When the silane coupling agent is added as an additive, it is fixed to the silica by its coupling reaction and further reacts with the rubber component, so that the dispersibility of the silica in the rubber and the reinforcing power are improved.

It is known to perform the kneading at a certain temperature for a longer period of time desirably for silica to react effectively with the silane coupling agent. In a low temperature environment, the coupling reaction between silica and a silane coupling agent is less likely. On the other hand, an excessively high temperature leads to crosslinking of the rubber, which increases the viscosity rapidly and leads to gelation.

When a rubber component is kneaded in a mixer with silica and a silane coupling agent, the internal temperature of the mixer rises due to the heat generated by the viscous flow of the rubber and the heat associated with the coupling reaction. As a result, the temperature reaches a value at which a gel is formed within a short time, and thus there is a problem that insufficient time is available for the coupling reaction.

Unexamined Published Japanese Patent Application (Kokai) JP-A-2004-352 831 discloses a method in which, prior to the addition of the silane coupling agent, a kneading step is carried out using a closed Banbury mixer, while the coupling reaction after the addition of the silane coupling agent is carried out using a separate mixer which is not closed.

Unexamined Published Japanese Patent Application (Kokai) JP-A-2007-8 112 also discloses a method in which a kneaded rubber composition is applied to a pair of kneading drums at a temperature slightly below the temperature range suitable for the coupling reaction, wherein the shearing force exerted by the rollers results in self-generation of heat for the coupling reaction.

• (3) Nunmehr folgt eine Beschreibung des B-Knetens. Wie in der ungeprüften veröffent-lichten Japanischen Patentanmeldung (Kokai) JP-A-2007-320 184 beschrieben, wird der Schritt des B-Knetens im allgemeinen bei einer Temperatur durchgeführt, die niedriger als die Temperatur ist, bei der der Schritt des A-Knetens erfolgt. Der Grund ist folgender. Beim Schritt des B-Knetens werden Vulkanisationskomponenten als Zusätze zugegeben. Wenn das Material bei einer hohen Temperatur gehalten wird, kann die Temperatur des Materials beim Verkneten folglich übermäßig hoch werden, was dazu führen kann, dass die noch unzureichend verknetete Gummizusammensetzung vernetzt.

The Methods of the Unexamined Published Japanese Patent Application (Kokai) JP-A-2004-352 831 and JP-A-2007-8 112 however, require mixers and rollers dedicated to coupling reactions. These documents do not disclose a method of kneading within a suitable temperature range without increasing the space required for the equipment.

• (3) Next is a description of B-kneading. As in the unexamined Published Japanese Patent Application (Kokai) JP-A-2007-320184 described, the step of B-kneading is generally carried out at a temperature which is lower than the temperature at which the A-kneading step takes place. The reason is the following. In the step of B-kneading, vulcanization components are added as additives. Consequently, when the material is kept at a high temperature, the temperature of the material upon kneading may become excessively high, which may cause the still insufficiently kneaded rubber composition to crosslink.

When such a phenomenon occurs, the hardness of the rubber increases, and the moldability becomes worse. In addition, when insoluble sulfur is used as the vulcanizing component, the sulfur can be converted into a soluble form at a high temperature, resulting in blooming, resulting in adhesion failure.

If rubber components are kneaded in a mixer, the internal temperature of the mixer rises z. Due to the heat generated by the viscous flow of the rubber. If the kneading takes place in particular with added vulcanization components, crosslinking takes place as soon as the Temperature reaches about 120 ° C. Conventionally, it was therefore common to drain the contents from the mixer as soon as this temperature was reached. In this case, however, the vulcanizing agents can not be kneaded for a sufficient time, resulting in their being poorly distributed.

A rubber composition having poorly distributed vulcanizing agents is later formed into a product containing foreign matters composed of vulcanization accelerators such as a guanidine compound. In addition, the finished product may have the problem of multiple defects such as uneven color of the surface and the formation of internal pores, so that the amount of scrap increases.

Unexamined Published Japanese Patent Application (Kokai) JP-A-2007-320184 discloses a structure having a cooling device for reducing the internal temperature of a mixer. Such a cooling device not only increases the space required for the system, but also increases the production costs significantly. The internal temperature of the mixer is also largely influenced by the performance and functions of the cooling device and can not always be kept under the desired conditions at all times.

Brief description of the invention

In view of the above problems, it is an object of the present invention to provide a rubber processing apparatus which can maintain the temperature during processing of the rubber in a range desired for each step and a processing method thereof.

In order to achieve the above object, the rubber processing apparatus of the present invention has the following:
a closed kneading chamber;
a filling opening for filling a material in the kneading chamber;
a stirring rotor (hereinafter referred to as a rotor) for stirring the material in the kneading chamber;
a control unit for automatically controlling the rotational speed of the rotor; and
a temperature sensor for detecting the temperature in the kneading chamber and transmitting the detected information regarding the actual temperature to the control unit;
wherein the control unit automatically regulates the rotational speed with a PID control configured to attempt to match the actual temperature with the target temperature until a control time set for the state in which the one has elapsed Gum component containing material in the kneading chamber is present, based on the information concerning the actual temperature and the information concerning the set target temperature.

In particular, the controller may be configured to automatically control the speed of the motor that rotates the rotor.

The material may be natural rubber or a rubber containing 50% or more natural rubber. In this case, the target temperature may be set to a value lower than the lower limit of the temperature at and above which the natural rubber vulcanizes, so that the apparatus of the present invention performs mastication for a longer period of time within a suitable temperature range.

The material may also contain a rubber component, silica and a silane coupling agent. In this case, the target temperature may be set at a value lower than the lower limit of the temperature at which the rubber component gels and above the lower limit of the temperature at which the coupling reaction of silica with the silane coupling agent occurs, so that the device of the present invention kneading for a longer period of time within a temperature range suitable for the coupling reaction.

The material may further contain a rubber component and a vulcanizing agent. In this case, the target temperature may preferably be set at a temperature of less than 120 ° C, and more preferably 110 ° C or less, or a value lower than the lower limit of the temperature at which the rubber component starts to crosslink, so that the apparatus of the present invention Distributing the vulcanizing agent improves while preventing the progress of the crosslinking.

According to the present invention, a control unit is provided to perform an automatic PID control for the rotational speed of the rotor so that the temperature within the kneading chamber can be kept within a range for a predetermined period of time. This allows stirring and kneading in the kneading chamber for a predetermined period of time while maintaining the desired temperature.

In other words, the temperature is maintained for a longer period of time within a temperature range suitable for each step, so that the production of rubber is compared with a conventional method in which the rubber material is discharged as soon as a predetermined temperature is reached with excellent properties becomes possible.

Short description of the drawing figures

Show it:

1 a schematic representation of the structure of a device according to the invention for processing rubber;

2 a flow chart showing the flow of Mastizierverfahrens performed in the device according to the invention;

3 (a) and 3 (b) graphs each showing the time change of the temperature actually measured within the kneading chamber and the time variation of the revolutions of the motor, the temperature and the revolutions being controlled by the control unit of the apparatus according to the invention with a PID control;

4 a flow chart showing the flow of the method of A-kneading, which is performed in the apparatus according to the invention; and

5 a flow chart showing the flow of the method for B-kneading, which is performed in the device according to the invention.

Detailed description of the invention Structure of the device

1 is a schematic representation of a device according to the invention 1 for processing rubber. The device according to the invention is a closed-type mixer comprising a cylinder 2 for the up and down movement of a piston 4 , a filling opening 3 for filling the materials to be processed, a kneading chamber 5 for kneading the materials and a bottom flap 7 for dispensing the kneaded rubber. The piston 4 Its upward and downward movements serve to adjust the pressure inside the kneading chamber 5 ,

The kneading chamber 5 is with a pair of rotors 6 to agitate the materials, and each rotor is driven by a motor (not shown) about an axis of rotation 12 turned. The kneading chamber 5 is also with a temperature sensor 13 equipped to detect the temperature inside the chamber. The temperature sensor 13 can z. B. on the inside of the bottom flap 7 are located.

The speed of the motor to rotate the rotor 6 is in accordance with a control signal from the control unit 11 regulated. The control unit 11 Controls the speed of the motor based on information provided by the temperature sensor 13 has been sent, which is the internal temperature of the kneading chamber 5 concerns. The engine may be of any type suitable for controlling the speed according to the control unit 11 free to change, and may, for. B. be an inverter motor.

In particular, the speed of the motor is subjected to a PID control for which the control unit 11 a PID arithmetic processing unit, wherein the control is based on calculations of the proportional terms (P), integral terms (I) and differential terms (D) calculated from the deviation of the actual temperature "Tp" from the target temperature "Ts", the actual Temperature inside the kneading chamber 5 from the temperature sensor 13 is measured.

In other words, the PID calculation processing unit determines the rotational speed of the engine on the basis of the summation of control variables determined by three effects; ie one Proportional effect (P), which gives a control variable in relation to the difference (deviation "e") between the actual temperature "Tp" and the target temperature "Ts", wherein the actual temperature inside the kneading chamber 5 from the temperature sensor 13 is measured; an integral action (I) which gives a control variable by integrating the deviation "e" along the time axis; and a differential action (D) which gives a control variable from the slope or the differential value of the variation of the deviation "e".

masticating

2 Fig. 3 is a flow chart showing the procedure of the rubber processing method (masticating method) used in the apparatus of the present invention 1 is carried out. The natural rubber to be masticated is inserted into the device 1 given (step S1); the values for the target temperature "Ts" and the setting time for the control "tm" are inputted (step S2); and the control unit 11 starts the PID control for the motor based on these values (step S3).

In other words, it determines a control signal from the control unit 11 the speed of the motor and thus the speed (ie, the speed of stirring) of the rotor 6 , The control unit 11 can before before the step 51 Information regarding the target temperature "Ts" and the set time for the control "tm" obtained.

The control unit 11 PID control continues to control the speed of the motor until the control time "t" elapsed from the start of control reaches or exceeds the set time for control "tm"("No" in S4). As already described, the specific control includes a change in the rotational speed by a small amount based on the deviation of the actual temperature "Tp" from the target temperature "Ts", the integral value of the deviation and the differential value of the deviation, the actual temperature in the kneading chamber 5 from the temperature sensor 13 is measured.

The value of the target temperature "Ts" set in step S2 may preferably be slightly lower than the upper limit of the temperature at which and below which the rubber does not vulcanize without the peptizer. The reason is that even if the control unit 11 is configured for PID control, the actual temperature may exceed the target temperature "Ts" slightly and temporarily during the control process. In other words, the target temperature "Ts" may preferably be set to such a value that the actual temperature "Tp" in the kneading chamber 5 the target temperature "Ts" may temporarily exceed during the control process temporarily.

When the control time "t" reaches or exceeds the setup time for the control "tm"("Yes" in step S4), the control unit ends 11 the PID control of the engine, and the masticated rubber gets out of the bottom flap 7 delivered (step S5). The set time for the control "tm" should be longer than the time "tc" required to give the rubber sufficient plasticity.

3 (a) Fig. 10 is a graph showing the changes of the actual temperature "Tp" in the kneading chamber 5 and the speed of the motor during the PID control of the control unit 11 inside the device according to the invention 1 , 3 (b) is an enlarged view of area A in FIG 3 (a) ,

As in 3 shown, the engine speed is changed by a small amount (up or down), so that the actual temperature "Tp" in the kneading chamber 5 over a longer period almost the same value as the target temperature "Ts" can be maintained. By keeping the temperature in this range for a certain period of time, the masticated rubber can be given sufficient plasticity. In the in 3 As shown, the target temperature "Ts" was set at 90 ° C, and the PID control made it possible to keep the actual temperature "Tp" within a range of 85 ° C to 98 ° C.

In the in 2 The flowchart shown is the control unit 11 configured to PID control each time a natural rubber lot is filled. It should be noted that in practice, the control unit can be configured so that the user can choose whether or not to apply the PID control.

The device according to the invention allows the holding of the internal temperature of the kneading chamber 5 over a predetermined period of time, so that the production of masticated rubber with sufficiently high plasticity is possible only by mechanical masticating. Since it is no longer necessary to chemically masticate with a peptizer, the amount of chemical of the masticated gum is almost completely homogenised. and consequently, the chemical properties of the masticated rubber product are stabilized. The following examples provide detailed explanations of other peculiarities of these effects.

A-kneading

Now A-kneading will be explained. 4 Fig. 3 is a flow chart graphically showing the procedure of the rubber processing method (A kneading method) used in the apparatus of the present invention 1 is carried out. A gum component, silica, and a silane coupling agent are introduced into the device 1 given (step S11); the values for the target temperature "Ts" and for the setting time for the control "tm" are inputted (step S12); and the control unit 11 starts on the basis of these values with the PID control of the motor (step S13).

In other words, it determines a control signal from the control unit 11 the speed of the motor and thus the speed (ie, the speed of stirring) of the rotor 6 , The control unit 11 For example, before the step S11, information regarding the target temperature "Ts" and the setup time for the control "tm" may be obtained.

It should be noted that during step S11 the rubber component, silica and silane coupling agent are separated into the device 1 can be added or the rubber component and silica for a predetermined stirring process can be filled first before the silane coupling agent is added.

The control unit 11 The control of the rotational speed of the engine by the PID control continues until the control time "t" elapsed from the start of the control reaches or exceeds the setup time for the control "tm"("No" in step S14). As already described, the specific control includes a change of the rotational speed by a small amount on the basis of the deviation of the actual temperature "Tp" from the target temperature "Ts", the integral value of the deviation and the differential value of the deviation, the actual temperature in the kneading chamber 5 from the temperature sensor 13 is measured.

The target temperature "Ts" set in step S12 may preferably be slightly lower than the lower limit of the temperature at and above which the rubber component gels. The reason is that even if the control unit 11 is configured for PID control, the actual temperature may exceed the target temperature "Ts" slightly and temporarily during the control process.

In other words, the target temperature "Ts" may preferably be set such that the actual temperature "Tp" in the kneading chamber 5 the target temperature "Ts" may exceed slightly and temporarily during the control process. The target temperature "Ts" should be higher than the lower limit of the temperature at and above which the coupling reaction between silica and the silane coupling agent takes place.

When the control time "t" reaches or exceeds the setup time for the control "tm"("Yes" in step S14), the control unit ends 11 the PID control of the engine, and the mixed rubber composition gets out of the bottom flap 7 delivered (step S15).

The set time for the control "tm" set in step S12 should be longer than the time "tc" required for a sufficient coupling reaction between the silica and the silane coupling agents. Specifically, when considering a time "ti" that has elapsed since the start of the control until the actual temperature "Tp" reaches a temperature range suitable for the coupling reaction, the response time for the control "tm" may preferably be equal to or longer than the sum of times "tc" and "ti".

When the A-kneading according to the in 4 Flowchart shown, it has been shown that there is a change in the speed of the motor by a small amount (up or down), as shown in 3 shown, allows the actual temperature "Tp" in the kneading chamber 5 over a longer period of time almost equal to the target temperature "Ts" to keep.

Holding the temperature longer than the above period "ti" enables a sufficient coupling reaction of the silane coupling agent in the kneading chamber 5 , On the basis of in 3 It has been confirmed that the PID control makes it possible to keep the actual temperature "Tp" for the target temperature "Ts" of 155 ° C in the range of 150 ° C to 158 ° C.

In the in 4 The flowchart shown is the control unit 11 configured to perform a PID control at any time after filling the silane coupling agent. In practice, the control unit may be configured so that the user can choose whether to use PID control or not.

The gum component to be charged contains a terminal-modified diene rubber having a number-average molecular weight in the range of 150,000 to 400,000. Examples of the diene rubber to be terminal-modified may include: a butadiene rubber (BR; cis content, with cis-1,4 of 90% or more, and BR containing syndiotactic 1,2-polybutadiene (SPB)), styrene-butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR) , a rubber of a styrene-isoprene copolymer and a rubber of a butadiene-isoprene copolymer, more preferably belong to BR or SBR, and even more preferably include, but are not limited to SBR.

The terminal-modified diene rubber may be a diene rubber whose polymer ends have been modified with a modifier by any method known in the art. In particular, the modifying agents may include a tin compound, an aminobenzophenone compound, an isocyanate compound, a diglycidylamine compound, a cyclic imine compound, a halogenated alkoxysilane compound, a glycidoxypropylmethoxy silane compound, a neodymium compound, an alkoxysilane compound and a combination of an amine compound and the alkoxysilane compound.

The silane coupling agent used for kneading is not particularly limited so far as it contains sulfur in its molecule, and it may be any silane coupling agent which is mixed in the rubber composition with silica.

Examples thereof include sulfide silanes such as bis (3-triethoxysilylpropyl) tetrasulfide (e.g., "Si 69" from Degussa AG), bis (3-triethoxysilylpropyl) disulfide (e.g., "Si 75" from Degussa AG), Bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) tetrasulfide and bis (2-trimethoxysilylethyl) disulfide; Mercaptosilanes such as γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, mercaptopropylmethyldimethoxysilane, mercaptopropyldimethylmethoxysilane and mercaptoethyltriethoxysilane; and blocked mercaptosilanes such as 3-octanoylthio-1-propyltriethoxysilane and 3-propionylthiopropyltrimethoxysilane.

The silane coupling agent may preferably be added in an amount ranging from 2 to 25 parts by weight, and more preferably from 5 to 15 parts by weight, based on 100 parts by weight of silica.

As described above, the apparatus of the present invention can be successfully used for the step of A-kneading because the temperature inside the kneading chamber is maintained for a given period of time, allowing kneading for a longer period of time within the temperature range suitable for the coupling reaction is. This allows the production of rubber products with excellent properties. The following examples provide detailed explanations of specifics of these effects.

B-kneading

The following is a description of B-kneading. 5 Fig. 3 is a flow chart showing the procedure of the method of processing rubber (B-kneading) used in the apparatus of the present invention 1 is carried out. A gum composition, vulcanizing agent and optional vulcanization accelerator are added to the device 1 given (step S21); values for the target temperature "Ts" and for the set time for the control "tm" are inputted (step S22); and the control unit 11 starts on the basis of these values with the PID control of the motor (step S23).

In other words, it determines a control signal from the control unit 11 the speed of the motor and thus the speed (ie, the speed of stirring) of the rotor 6 , The control unit 11 may previously obtain information regarding the target temperature "Ts" and the setup time for the control "tm" before the step S21.

It should be noted that the rubber composition introduced in step S21 may be A-kneaded rubber obtained by kneading a rubber component with an additive containing no vulcanization components such as a vulcanizing agent and a vulcanization accelerator.

In addition, at step S21, the rubber composition, the vulcanizing agent and the vulcanization accelerator may be separately introduced into the apparatus 1 may be added, or it may be filled an already stirred rubber composition containing a vulcanizing agent and a vulcanization accelerator.

The control unit 11 The control of the rotational speed of the engine by the PID control continues until the control time "t" elapsed from the start of the control reaches or exceeds the setting time for the control "tm"("No" in step S24). As already described, the specific control involves changing the speed by a small amount based on the deviation of the actual temperature "Tp" in the kneading chamber 5 from the temperature sensor 13 is measured from the target temperature "Ts", the integral value of the deviation and the differential value of the deviation.

The target temperature "Ts" set in step S22 may preferably be slightly lower than the lower limit of the temperature at which the rubber component starts to crosslink. The reason is that even if the control unit 11 is configured for PID control, the actual temperature during the control process may exceed the target temperature "Ts" slightly and temporarily. In other words, the target temperature "Ts" may preferably be set so that the actual temperature "Tp" in the kneading chamber 5 during the control process, the target temperature "Ts" can exceed something and temporarily.

When the control time "t" reaches or exceeds the setup time for the control "tm"("Yes" in step S24), the control unit ends 11 the PID control of the engine, and the mixed rubber composition gets out of the bottom flap 7 delivered (step S25).

The setting time for the control "tm" set in step S22 should be longer than the time "tc" required for the sufficient distribution of the vulcanizing agent in the rubber composition.

When the B-kneading according to the in 5 shown flowchart, it has been shown that there is a change in the speed of the motor by a small amount (up or down), as shown in 3 is shown makes it possible to keep the actual temperature "Tp" in the kneading chamber for a longer period almost equal to the target temperature "Ts". By keeping the temperature sufficiently long, the vulcanizing agent becomes sufficiently within the rubber composition in the kneading chamber 5 distributed. On the basis of in 3 As shown, it has been confirmed that the PID control makes it possible to keep the actual temperature "Tp" for a target temperature "Ts" of 95 ° C in the range of 92 ° C to 98 ° C.

In the in 5 The flowchart shown is the control unit 11 configured to PID control at any time after the rubber composition and a vulcanizing agent have been filled. In practice, the control unit may be configured so that the user can choose whether to use PID control or not.

In step S21, a rubber component containing materials similar to those used for the above-mentioned A-kneading step may be filled. In another embodiment, an A-kneaded rubber may be used with the rubber component kneaded with a predetermined additive. The predetermined additive is added as needed, and may include carbon black, silica, a silane coupling agent, zinc oxide, stearic acid, an aging inhibitor, and a plasticizer such as wax and oil.

The vulcanizing agent to be added may be a sulfur conventionally used for rubber, and may include powdered sulfur, already precipitated sulfur, insoluble sulfur, and highly dispersible sulfur. In order to impart sufficiently high rubber strength to the vulcanized rubber and to further improve the heat resistance and durability, the sulfur content may preferably be in the range of 0.1 to 2.0 parts by weight, and more preferably 0.1 to 1, 0 part by weight, based on 100 parts by weight of the rubber component.

The vulcanization accelerator may be of any type used for vulcanizing rubber, and vulcanization accelerators in the form of sulfenamide, thiuram. Thiazole, thiourea, guanidine, dithiocarbamate and combinations thereof.

As described above, the apparatus of the present invention can be successfully used for the step of B-kneading because the temperature inside the kneading chamber 5 for a given period is maintained, which allows a sufficient distribution of the vulcanizing agent while preventing crosslinking. This allows the production of rubber products with excellent properties. The following examples provide detailed explanations of special effects.

Examples

example 1

See Table 1; Example 1 shows the result when the device according to the invention 1 for mastication with PID control turned on, whereas Comparative Examples 1 and 2 show the results when mastication was done with the PID control disabled. Each value is listed as a relative value relative to a reference value (100) of Comparative Example 1. The following materials were used.

materials

• Natural rubber: RSS # 3
• Peptizer: a zinc salt of fatty acid containing from 5 to 10% by weight of DBD (2,2'-dibenzamido-diphenyldisulfide) (the constituent fatty acid consisting principally of a 16-carbon saturated fatty acid), "Aktiplast MS", of Rhein Chemie Rheinau GmbH,

When the above-mentioned materials are used, the lower limit of the temperature at which the rubber components vulcanize is about 180 ° C, and by stirring at this temperature of about 180 ° C, the mechanical masticating can proceed without causing vulcanization of the rubber comes. In particular, the temperature range may preferably be maintained at less than 110 ° C, and more preferably at less than 100 ° C.

In the following Example 1, the device according to the invention 1 used for stirring, with their PID control turned on to the temperature within the kneading chamber 5 to keep at 90 ° C in the above-described temperature range. Table 1 conditions Comparative Example 1 Comparative Example 2 example 1 added peptizer more peptizer kept at 90 ° C. natural rubber 100 100 100 peptizer 0.15 0.2 0 viscosity 100 96 95 TB 100 93 112

Comparative Examples 1 and 2 illustrate the cases where mechanical mastication occurred before the addition of the peptizer, followed by chemical mastication as in a conventional method. In Comparative Example 1, the added amount of the peptizer was 0.15, based on 100 parts of natural rubber, and in Comparative Example 2, the amount added was 0.2. Comparative Example 2 contains a larger amount of the peptizer.

Example 1 illustrates a case where the PID control with the device 1 the temperature was controlled so that the masticating according to the invention was carried out solely by mechanical mastication without the addition of a peptizer.

The following procedures were used for the measurements, and each result was converted into a relative value relative to Comparative Example 1.

viscosity

For the masticated rubber discharged from the mixer, the Mooney viscosity (ML _{1 + 4} ) was determined according to JIS K6300 with a Mooney viscometer with an L-shaped rotor under conditions including a preheat time of 1 minute, a revolution time of the rotor of 4 minutes, a temperature of 100 ° C and a speed of 2 rpm. If the value of this parameter is smaller, it means that the formability becomes even more outstanding.

Strength of the rubber (TB)

Tensile strength (TB (MPa)) was measured on dumbbell samples JIS No. 3 JIS K6251 measured. The TB value of Comparative Example 1 was taken as 100 and the results for Example 1 and Comparative Example 2 were normalized to this value of 100. If the TB value is higher, it means that the strength of the rubber is better and more advantageous.

Comparing Example 1 with Comparative Example 1 in Table 1, Example 1 shows a lower viscosity, indicating excellent moldability. In addition, Example 1 shows a higher TB value, indicating a higher strength of the rubber.

Comparing Comparative Example 1 with Comparative Example 2, Comparative Example 2 has a lower value of viscosity, so that it becomes clear that a larger amount of the peptizer shows an expected better moldability. Comparative Example 2, however, shows a TB value lower than that of Comparative Example 1, indicating the lower strength of the rubber. This implies that a larger amount of peptizer compared with Comparative Example 1 promotes the chemical reaction more, resulting in molecules that are extremely short in many places.

In Example 1, mastication alone was performed as a mechanical mastication without peptizer, so that the presence of extremely short molecules in the masticated gum is inhibited, thus avoiding the adverse influence of the peptizer on reducing strength. In addition, it allows the PID control of Vor-direction invention 1 to maintain the temperature in a temperature range of about 90 ° C for a predetermined period of time, so that even without chemical masticating, the production of masticated rubber having excellent moldability becomes possible.

Example 2

See Table 2; Examples 2 to 4 show the cases in which the device according to the invention 1 for A kneading with PID control turned on, whereas Comparative Examples 3 to 5 show the cases where PID control was turned off. Each value is given as a relative value in relation to the reference value (100) of Comparative Example 3. For the examples and comparative examples, the following materials were used.

materials

• Modified styrene-butadiene rubber (modified SBR): HPR340 (modified S-SBR, 10 wt% bound amount of styrene modified with amine and alkoxysilane) manufactured by JSR Corporation
• Untreated silica: "NIPSIL AQ", available from Tosoh Silica Corporation
• Silane coupling agent: bis (3-triethoxysilylpropyl) disulfide, "Si-75", manufactured by Degussa AG
• • Blocked mercaptosilane: a coupling agent of the formula (C _n H _{2n + 1} O) ₃ Si-C _m H _2m -S-CO-C _k H _{2k + 1} (n = 2, m = 3, k = 7), NXT ", from MOMENTIVE PERFORMANCE MATERIALS INC. produced
• • Oil: "Process X-140", available from Japan Energy Corporation

In the materials listed above, the lower limit of the temperature at and above which the rubber component gels is about 170 ° C, and the lower limit of the temperature at and above which the silica and silane coupling agent undergo coupling reaction is about 130 ° C. In other words, holding within a temperature range higher than about 130 ° C and lower than about 170 ° C while stirring enables the rubber components to undergo a sufficient coupling reaction while preventing gelation.

The temperature range may preferably be maintained at more than 140 ° C and less than 165 ° C, and more preferably at more than 145 ° C and less than 160 ° C. In the following examples 2 to 4 stirring took place in the kneading chamber 5 the device according to the invention 1 in the temperature range at about 150 ° C, while the PID control remained turned on. Table 2 conditions Comparative Example 3 Comparative Example 4 Comparative Example 5 Example 2 Example 3 Example 4 drained at 150 ° C drained at 160 ° C drained at 170 ° C held at 150 ° C for 1 minute held at 150 ° C for 5 minutes held at 150 ° C for 10 minutes viscosity 100 97 105 92 87 82 Payne effect 100 81 78 71 50 44 rolling resistance 100 100 99 101 98 95 tan δ 100 100 96 102 94 85

The following procedures were used for the measurements, and each result was converted into a relative value relative to Comparative Example 3.

viscosity

For the mixed rubber composition discharged from the mixer, the Mooney viscosity (ML _{1 + 4} ) was determined according to JIS K6300 with a L-shaped rotor Mooney viscometer under the conditions of a preheating time of 1 minute, a working time of the rotor of 4 minutes, a temperature of 100 ° C and a speed of 2 rpm. If the value of this parameter is smaller, it means that moldability becomes more excellent.

Payne effect

A part of each mixed rubber composition discharged from the mixer was used for the production of a test piece, and a rubber process analyzer was used to obtain the value for the Payne effect determined by the minimum value of the Shearing force was subtracted from the maximum value of the shear force, the shear forces being measured with a change in elongation from 0.5% to 45%.

As described above, each value is given as a relative value relative to the reference value of Comparative Example 3. If the Payne effect is lower, it means that the dispersibility of silica becomes even more excellent.

rolling resistance

The mixed rubber composition was discharged from the mixer and vulcanized at 150 ° C for 30 minutes to prepare a rubber for a tread used for the production of a test tire for evaluation of rolling resistance. The rolling resistance test was carried out according to JIS D4234 , The diameter of the drum was 1708 mm, the ambient temperature was 25 ° C, the test mode was the Force technique, and each result was obtained as a relative value with respect to the tire of Comparative Example 3 set at 100. If the value is smaller, it means that the rolling resistance is lower, and thus the economy with respect to the fuel becomes more excellent.

tan δ

The mixed rubber composition discharged from the mixer was vulcanized at 150 ° C for 30 minutes to prepare a test piece having a predetermined shape, and a UBM Ltd. manufactured by UBM Ltd. was used. made viscoelasticity spectrometer used to tan δ according to JIS K6394 at an initial elongation of 15%, a kinetic elongation of ± 2.5%, a frequency of 10 Hz and a temperature of 60 ° C. Each result is listed as a relative value to the reference value 100 for Comparative Example 3. If this value is smaller, it means that the amount of heat generated becomes smaller.

Table 2 shows that Examples 2 to 4 are low in viscosity and low in Payne effect in comparison with Comparative Examples 3 to 5, indicating their excellent moldability and excellent dispersibility of silica. A longer hold time reduces the rolling resistance and tan δ value, indicating low fuel consumption and low heat generation.

Comparative Examples 3 to 5 show that as the temperature inside the kneading chamber increases, the value for the Payne effect becomes lower and the dispersibility of silica becomes better. However, the rolling resistance and tan δ are not significantly affected by the temperature rise. The higher viscosity also means that the silica aggregates again. In contrast, Examples 2 to 4 show that a longer hold time decreases the values for viscosity, rolling resistance and tan δ, respectively.

Example 3

See Table 3; Example 5 shows the case where the device according to the invention 1 was used with switched PID control for the B-kneading, and the comparative examples 6 and 7 show the cases in which the inventive device 1 was used with the PID control switched off for B-kneading.

In Comparative Example 6, kneading was carried out with the PID control switched off and was stopped as soon as the temperature inside the kneading chamber 5 had reached a value of 110 ° C. The kneading time at this end time was 60 seconds.

In Comparative Example 7, kneading was carried out with the PID control switched off and was stopped as soon as the temperature inside the kneading chamber 5 had reached a value of 126 ° C. The kneading time was 120 seconds at this end time.

In the case of Example 5, kneading was carried out in the device according to the invention 1 with PID control on, which controls the temperature in the kneading chamber 5 was held at 110 ° C, and the kneading was stopped when the kneading time as in the case of Comparative Example 7 had reached a value of 120 seconds.

In Table 3, the values for the vulcanization rate and the time of scorching are given as relative values relative to the reference value (FIG. 100 ) of Comparative Example 6. Further, in each Example and Comparative Example, an A-kneaded rubber obtained by kneading the following materials was kneaded with a vulcanizing agent and a vulcanization accelerator.

A-kneaded rubber material

• Modified styrene-butadiene rubber (modified SBR): HPR340 (modified S-SBR, 10 wt% bound amount of styrene modified with amine and alkoxysilane) manufactured by JSR Corporation
• Untreated silica: "NIPSIL AQ", available from Tosoh Silica Corporation
• Silane coupling agent: bis (3-triethoxysilylpropyl) disulfide, "Si-75", manufactured by Degussa AG
• • Blocked mercaptosilane: coupling agent of the formula (C _n H _{2n + 1} O) ₃ Si-C _m H _2m -S-CO-C _k H _{2k + 1} (n = 2, m = 3, k = 7), "NXT , By MOMENTIVE PERFORMANCE MATERIALS INC. produced
• • Oil: "Process X-140", available from Japan Energy Corporation

vulcanizing

• • "5% Oil Treated Sulfur", from Hosoi Chemical Industry Co., Ltd. produced

vulcanization accelerators

• N-cyclohexyl-2-benzothiazolyl sulfenamide, "NOCCELER CZ-G (CZ)", by Ouchi Shinko Chemical Industy Co., Ltd. produced

When using the above-mentioned materials, the lower limit of the temperature at which the rubber component starts to crosslink is about 120 ° C. Preferably, a temperature range of less than about 120 ° C, and more preferably 110 ° C or less, is maintained with stirring to prevent the crosslinking of the rubber components and to sufficiently distribute the vulcanizing agent and the vulcanization accelerator.

As already described, the stirring was carried out in Example 2 in the device according to the invention 1 with PID control switched on, so that the temperature inside the kneading chamber 5 in the above-described range, at 110 ° C, is maintained. Table 3 conditions Comparative Example 6 Comparative Example 7 Example 5 delivered at 110 ° C. delivered at 125 ° C. kept at 110 ° C Kneading time (s) 60 120 120 vulcanization 100 105 95 scorch 100 45 102

For the measurements, the following procedures were used, and each result was converted into a relative value with respect to Comparative Example 6.

vulcanization

The mixed rubber composition discharged from the mixer was subjected to a vulcanization test at 160 ° C using a rheometer for 60 minutes, the control time being measured from the beginning of the measurement to the time point at which the difference between the maximum value M _H and the Minimum value M _{L of} the torque (ie M _H - M _L ) was 50%. If the value is smaller, it indicates that the time required for vulcanization becomes shorter and distributing the vulcanizing agent is advantageous.

scorch

For the mixed rubber composition discharged from the mixer, the scorch time (Sco (t5)) was determined according to JIS-K 6300-1 measured at 125 ° C. If this value is higher, it indicates that the mixed rubber composition is less vulcanized at the time of discharge from the mixer.

Comparative Example 7 shows a value for the scorching time, which is significantly lower than that of Comparative Example 6. This indicates that in the case of Comparative Example 7, the temperature within the kneading chamber 5 at the time of discharge was higher than that in Comparative Example 6, and as a result, the vulcanization in kneading in Comparative Example 7 was more advanced.

As for the vulcanization rate, Comparative Example 7 shows a higher value as compared with Comparative Example 6, indicating that the higher temperature reduced the dispersibility of the vulcanizing agents.

Comparing Example 5 with Comparative Example 6, Example 5 shows a lower cure rate value. In contrast to Comparative Example 6, in which stirring was stopped when the temperature reached 110 ° C, Example 5, in which the PID control kept the stirring temperature at about 110 ° C for a predetermined period of time, made possible in comparison with Comparative Example 6 a longer stirring, so that the vulcanizing agent could be better distributed.

Comparing Example 5 with Comparative Example 7, Comparative Example 7 shows a significantly lower scorch time. Comparing Example 5 with Comparative Example 6, the difference in the scorch time is almost unchanged. This shows that the method according to Example 5 allows the kneading for a longer period without the vulcanization is promoted.

As described above, according to the method of the present invention, Example 5 makes it possible to maintain the kneading temperature at a temperature lower than that for a predetermined period of time Lower limit of the temperature at which crosslinking occurs so that spreading of the vulcanizing agent is improved while preventing crosslinking.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 7-227845 [0004, 0005]
• JP 2004-352831 A [0004, 0014, 0016]
• JP 2007-8112 A [0004, 0015, 0016]
• JP 2007-320184 A [0004, 0016, 0020]

Cited non-patent literature

• JIS K6300 [0086]
• JIS K6251 [0087]
• JIS K6300 [0095]
• JIS D4234 [0098]
• JIS K6394 [0099]
• JIS K 6300-1 [0111]

Claims (13)

Device for processing rubber, comprising: - a closed kneading chamber ( 5 ); - a filling opening ( 3 ) for filling a material in the kneading chamber ( 5 ); A rotor ( 6 ) for stirring the material in the kneading chamber ( 5 ) a control unit ( 11 ) for automatically controlling the speed of the rotor ( 6 ); and a temperature sensor ( 13 ) for detecting the temperature in the kneading chamber ( 5 ) and sending the detected information on the actual temperature to the control unit ( 11 ); - wherein the control unit ( 11 ) automatically regulates the rotational speed with a PID control configured to make the actual temperature coincide with the target temperature until a control time set for the state in which the one containing rubber component has expired Material in the kneading chamber ( 5 ), on the basis of the information concerning the actual temperature and the information concerning the set target temperature. A rubber processing apparatus according to claim 1, wherein said material is natural rubber or a rubber compound containing 50% or more natural rubber. A rubber processing apparatus according to claim 1, wherein said material contains a rubber component, silica and a silane coupling agent. A rubber processing apparatus according to claim 1, wherein said material contains a rubber component and a vulcanizing agent. A method of processing rubber comprising the steps of: - providing a material in a kneading chamber ( 5 ) with a rotor ( 6 ) whose speed is controlled by a control unit ( 11 ) can be controlled automatically, the kneading chamber ( 5 ) is closed and an internal temperature can be measured and sent, and the material contains a rubber component; Setting a control time and a target temperature in the control unit 11 ); and - stirring in the interior of the kneading chamber ( 5 ), wherein the speed is automatically controlled by a PID control configured to make the actual temperature coincide with the target temperature by the expiration of the set control time on the basis of the actual temperature Information and a target temperature information after the above two steps have been completed. A method of processing rubber according to claim 5, wherein said material comprises natural rubber or a rubber compound having 50% or more natural rubber. A method of processing rubber according to claim 6, the method is for the production of masticated rubber and wherein the target temperature is set to a value lower than the lower limit of the temperature at or above which the natural rubber is vulcanized. A method of processing rubber according to claim 5, wherein the material comprises a rubber component, silica and a silane coupling agent. A method of processing rubber according to claim 8, wherein the target temperature is lower than the lower limit of the temperature at which the rubber component gels and is higher than the lower limit of the temperature at which the coupling reaction of silica with a silane coupling agent occurs. A method of processing rubber according to claim 9, wherein the rubber component comprises a modified styrene-butadiene rubber modified with an amine and an alkoxysilane, and wherein the silane coupling agent contains bis (3-triethoxysilylpropyl) disulfide or a blocked mercaptosilane. A method of processing rubber according to claim 5, wherein the material comprises a rubber component and a vulcanizing agent. A method of processing rubber according to claim 11, wherein the target temperature is a temperature lower than the lower limit of the temperature at which the rubber component starts to crosslink. A method of processing rubber according to claim 12, wherein the target temperature is a temperature of less than 120 ° C and preferably 110 ° C or less.

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